// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2011 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include "lapack_common.h"
#include <Eigen/Eigenvalues>

// computes eigen values and vectors of a general N-by-N matrix A
EIGEN_LAPACK_FUNC(
	syev,
	(char* jobz, char* uplo, int* n, Scalar* a, int* lda, Scalar* w, Scalar* /*work*/, int* lwork, int* info))
{
	// TODO exploit the work buffer
	bool query_size = *lwork == -1;

	*info = 0;
	if (*jobz != 'N' && *jobz != 'V')
		*info = -1;
	else if (UPLO(*uplo) == INVALID)
		*info = -2;
	else if (*n < 0)
		*info = -3;
	else if (*lda < std::max(1, *n))
		*info = -5;
	else if ((!query_size) && *lwork < std::max(1, 3 * *n - 1))
		*info = -8;

	if (*info != 0) {
		int e = -*info;
		return xerbla_(SCALAR_SUFFIX_UP "SYEV ", &e, 6);
	}

	if (query_size) {
		*lwork = 0;
		return 0;
	}

	if (*n == 0)
		return 0;

	PlainMatrixType mat(*n, *n);
	if (UPLO(*uplo) == UP)
		mat = matrix(a, *n, *n, *lda).adjoint();
	else
		mat = matrix(a, *n, *n, *lda);

	bool computeVectors = *jobz == 'V' || *jobz == 'v';
	SelfAdjointEigenSolver<PlainMatrixType> eig(mat, computeVectors ? ComputeEigenvectors : EigenvaluesOnly);

	if (eig.info() == NoConvergence) {
		make_vector(w, *n).setZero();
		if (computeVectors)
			matrix(a, *n, *n, *lda).setIdentity();
		//*info = 1;
		return 0;
	}

	make_vector(w, *n) = eig.eigenvalues();
	if (computeVectors)
		matrix(a, *n, *n, *lda) = eig.eigenvectors();

	return 0;
}
